The Bambangan—A Biological Poser


Most Sabahans know about the Bambangan fruit (scientific name – Mangifera pajang, which makes it a species of mango (pic above and here) and its uses in the preparation of local cuisine. But here’s a question for you: how many of you know that the plant is relatively rare within its natural habitat—a wild species of mango that is only mostly found in the west coastal plains of Sabah, and in some parts of Sarawak and Kalimantan? Indeed this plant is listed under the IUCN’s (International Union for Conservation of Nature) Red List of Threatened Species. And, here’s a biological poser for you:

Let’s recall your high school biology. All plants have dispersal strategies to make their seeds as far-ranging as possible. The dispersal of progenies beyond the canopy of the parent is important to prevent parent-seedling competition and to encourage colonisation of new areas. It also helps seeds to escape the attentions of seed-eating animals. Some that make use of the wind to disperse their seeds are light, winged, fluffy, etc., such as Kapok, Angasana or Lalang. Others have seeds that are hooked or barbed so these can snagged on to animal furs and be carried far away. Others are buoyant so they can be swept downstream or carried by currents and tides to faraway places. Others entice dispersal agents such as birds, insects and animals with delicious (but no necessarily so to humans; chilli padi comes to mind) seed-carrying fruits so that they may be carried to other places before being eaten, or eaten in situ and seeds, that have evolved to withstand the rigours of the animal’s digestive juices, defecated elsewhere. Whatever the dispersal strategy, the point is that the plant have evolved to equip its seeds with the best means to take advantage of the dispersal agent in mind, well…plants don’t think, but you know what I mean. Many fruits have evolved their size, colour, odour, seed casing, and other adaptive features during millions of years of association with animals as dispersal agents.

Anyway, back to the Bambangan. A Bambangan fruit that is fully grown and ripe is the size of two adult fists clasped together, and inside the thick skin and fruit pulp is a large seed protected by a tough pod. In fact, it is among the largest seeds in the world. What are/were the dispersal animals for Bambangan? With seeds this big, they must have been large animals but the only indigenous megafauna now in Borneo are the tembadaus, elephants and rhinos (and they are few and far between, and certainly, not in the West Coast of Sabah).

This tree must surely count as among the biological anachronisms mentioned by Connie Barlow in The Ghosts of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms. The term applies to plants that some time in the past thirty or forty million years have evolved fruits intended to attract very large mammals. These fruits, and I suspect, this includes the Bambangan, are adapted primarily for animals that have been extinct for thousand of years. “Year after year these plants produce fruits that make little sense today. Some fruits simply rot on the ground beneath the parent plant. Others are raided by seed predators or plundered by pulp thieves. Whether rotted, raided, or plundered, viable seeds are rarely dispersed. The plants not only remember the great mammals of the Pleistocene and before; they expect gomphotheres, ground sloths, toxodons, and their ilk to show up any day now. Thirteen thousand years is not enough time for plants to notice and genetically respond to the loss.”

So, next time you buy ripe Bambangan, help the tree. Plant one, you will enjoy its fruits in 10 years while helping it to proliferate. I took a picture of the above tree in Kg. Hungab, Penampang.

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3 thoughts on “The Bambangan—A Biological Poser

  1. Great post, Rayner! I’m imagining.. some huge prehistoric mammals roaming this land and snacking on bambangans! Will plant a seed next time I’m at the kampung.

  2. Come to think of it, the Bundu may also be one of these. When it ripens, it immediately falls down; it does not hang alluringly for some giant flying fox to cart it away. Yet when the ripe sits on the ground, how many animals can actually transport it as it is far away? The seed itself is toxic as some of us kids can attest to when we suffered from “Bunduoan” (severe allergic reactions to the ripe seed chemicals). The tree has evolved it’s seeds to be not meant to be munched but instead swallowed whole together with the pod by a long-extinct large mammal. Pity the Bundu, still waiting in hope for it’s dispersal partner…
    Chemica

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